Generally, a valve for controlling a flow rate of working fluid according to an electromagnetic force is used in hydraulically operated construction machines and industrial machines.
JP2002-39429A describes a two-stage pilot electromagnetic valve with a main valve seat allowing communication between an inlet hole and an outlet hole, a main valve body for opening and closing the main valve seat, a first pilot valve seat allowing communication between a back pressure chamber of the main valve body and the outlet hole, a first pilot valve body for opening and closing the first pilot valve seat, a second pilot valve seat allowing communication between a back pressure chamber of the first pilot valve body and the outlet hole and a second pilot valve body for opening and closing the second pilot valve seat by an electromagnetic force.
In this two-stage pilot electromagnetic valve, the large main valve body is driven to open and close by a pilot pressure adjusted in two stages to execute a flow rate control.